Wireless devices and systems including examples of compensating power amplifier noise

ABSTRACT

Examples described herein include methods, devices, and systems which may compensate input data for non-linear power amplifier noise to generate compensated input data. In compensating the noise, during an uplink transmission time interval (TTI), a switch path is activated to provide amplified input data to a receiver stage including a coefficient calculator. The coefficient calculator may calculate an error representative of the noise based partly on the input signal to be transmitted and a feedback signal to generate coefficient data associated with the power amplifier noise. The feedback signal is provided, after processing through the receiver, to a coefficient calculator. During an uplink TTI, the amplified input data may also be transmitted as the RF wireless transmission via an RF antenna. During a downlink TTI, the switch path may be deactivated and the receiver stage may receive an additional RF wireless transmission to be processed in the receiver stage.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.16/118,017 filed Aug. 30, 2018 and issued as U.S. Pat. No. 10,333,567 onJun. 25, 2019, which is a continuation of U.S. Patent Application Ser.No. 15/986,555 filed May 22, 2018. The aforementioned applications andissued patent, are incorporated herein by reference in its entirety, forany purpose.

BACKGROUND

Digital signal processing for wireless communications, such as digitalbaseband processing or digital front-end implementations, may beimplemented using hardware (e.g. silicon) computing platforms. Forexample, multimedia processing and digital radio frequency (RF)processing may be accomplished by an application-specific integratedcircuit (ASIC) which may implement a digital front-end for a wirelesstransceiver. A variety of hardware platforms are available to implementdigital signal processing, such as the ASIC, a digital signal processor(DSP) implemented as part of a field-programmable gate array (FPGA), ora system-on-chip (SoC). However, each of these solutions often requiresimplementing customized signal processing methods that arehardware-implementation specific. For example, a digital signalprocessor may implement a specific portion of digital processing at acellular base station, such as filtering interference based on theenvironmental parameters at that base station. Each portion of theoverall signal processing performed may be implemented by different,specially-designed hardware, creating complexity.

Moreover, there is an increasing interest in moving wirelesscommunications to “fifth generation” (5G) systems. 5G offers promise ofincreased speed and ubiquity, but methodologies for processing 5Gwireless communications have not yet been set. In some implementationsof 5G wireless communications, “Internet of Things” (IoT) devices mayoperate on a narrowband wireless communication standard, which may bereferred to as Narrow Band IoT (NB-IoT). For example, Release 13 of the3GPP specification describes a narrowband wireless communicationstandard.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a system arranged in accordancewith examples described herein.

FIG. 2 is a schematic illustration of an electronic device arranged inaccordance with examples described herein.

FIG. 3 is a schematic illustration of a wireless transmitter.

FIG. 4 is a schematic illustration of wireless receiver.

FIG. 5 is a schematic illustration of an example processing unitarranged in accordance with examples described herein.

FIG. 6 is a schematic illustration of a time frame for a time-divisionmultiplexing time period arranged in accordance with examples describedherein.

FIG. 7 is a schematic illustration of a power amplifier noisecompensation method in accordance with examples described herein.

FIG. 8 is a block diagram of a computing device arranged in accordancewith examples described herein.

FIG. 9 is a schematic illustration of a wireless communications systemarranged in accordance with aspects of the present disclosure.

FIG. 10 is a schematic illustration of a wireless communications systemarranged in accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

Examples described herein include wireless devices and systems which mayinclude examples of compensating power amplifier noise. Digitalpre-distortion (DPD) filters may be utilized to compensate nonlinearpower amplifier noise, such as power amplifier noise found in wirelessdevices and systems with power amplifiers. For example, an RF poweramplifier (PA) may be utilized in transmitters of wireless devices andsystems to amplify wireless transmission signals that are to betransmitted. Such nonlinear power amplifier noise from power amplifiersmay be difficult to model, and, accordingly, DPD filters are utilized tocompensate such nonlinear power amplifier noise, thereby reducing noisesintroduced into the wireless transmission signal from a power amplifierduring transmission. Conventional wireless devices and systems mayutilize specially-designed hardware to implement a DPD filter in awireless device or system. For example, a DPD filter may be implementedin a variety of hardware platforms, as part of a wireless transceiver ortransmitter.

As described herein, a coefficient calculator in a wireless device orsystem may utilize feedback after processing of a compensated wirelesstransmission signal to determine how efficiently the DPD filter iscompensating such wireless transmission signals. For example, indetermining how efficiently the DPD filter is performing compensationfor nonlinear power amplifier noise, the coefficient calculator maycalculate an error signal between an initial wireless transmissionsignal and the compensated, amplified wireless transmission signal toreduce error in a model of the DPD filter (e.g., coefficient datautilized to model a compensation filter). Conventional wireless devicesmay include a specific path with a receiver portion to process afeedback signal at a DPD filter, which may be inefficient in utilizingcomputational resources and/or board space to provide such a path forthe feedback. That specific path with the receiver portion to processthe feedback signal may be in addition to a wireless receiver path for awireless receiver portion of the wireless device. Accordingly, chiparchitectures in which the feedback signal is provided to a coefficientcalculator in an efficient scheme may be desired to reduce computationalresources needed and/or optimize the board space of that wireless chip.

In the examples described herein, a time division duplexing (TDD)configured radio frame is utilized in conjunction with a single receiverpath to provide both a feedback signal to a coefficient calculator andto receive wireless transmission signals, which may be received at awireless receiver portion of a wireless device. In accordance with theexamples described herein, a switch may activate a path to provide thefeedback signal through the wireless receiver path to the coefficientcalculator, when the wireless receiver path is not receiving an activewireless signal. For example, the wireless receiver path may not receivean active wireless signal during an uplink time period of a TDDconfigured radio frame. The uplink time period of the TDD configuredradio frame can be referred to as an uplink transmission time interval(TTI). Similarly, the downlink time period of the TDD configured radioframe can be referred to as a downlink transmission time interval (TTI).During an uplink TTI, the switch may be activated to provide thefeedback through the wireless receiver path to the coefficientcalculator. In providing the feedback over multiple uplink TTIs, thecoefficient calculator may provide the coefficients of a model thatcompensate for nonlinear power amplifier noise. Additionally, duringdownlink TTIs, the switch may deactivate the path that provides feedbackthrough the wireless receiver path, so that the wireless receiverportion of a wireless transceiver may receive wireless transmissionsignals, thereby providing for efficient TDD frames to both provide thefeedback signal to the coefficient calculator and to receive wirelesssignals using the same wireless receiver path.

FIG. 1 is a schematic illustration of a system 100 arranged inaccordance with examples described herein. System 100 includeselectronic device 102, electronic device 110, antenna 101, antenna 103,antenna 105, antenna 107, antenna 121, antenna 123, antenna 125, antenna127, wireless transmitter 111, wireless transmitter 113, wirelessreceiver 115, wireless receiver 117, wireless transmitter 131, wirelesstransmitter 133, wireless receiver 135 and, wireless receiver 137. Theelectronic device 102 may include antenna 121, antenna 123, antenna 125,antenna 127, wireless transmitter 131, wireless transmitter 133,wireless receiver 135, and wireless receiver 137. The electronic device110 may include antenna 101, antenna 103, antenna 105, antenna 107,wireless transmitter 111, wireless transmitter 113, wireless receiver115, and wireless receiver 117. In operation, electronic devices 102,110 can communicate wireless communication signals between therespective antennas of each electronic device. In an example of a TDDmode, wireless transmitter 131 coupled to antenna 121 may transmit toantenna 105 coupled to wireless receiver 115 during an uplink period ofthe TDD configured radio frame, while, at the same time or during atleast a portion of the same time, the wireless transmitter may alsoactivate a switch path that provides a feedback signal to a coefficientcalculator of wireless transmitter 131.

The coefficient calculator of wireless transmitter 131 may provide thecoefficients that are utilized in a model to at least partiallycompensate for power amplifier noise internal to the wirelesstransmitter 131. The wireless transmitter 131 may include a poweramplifier that amplifies wireless transmission signals before providingsuch respective wireless transmission signals to the antenna 121 for RFtransmission. In some examples, the coefficient calculator wirelesstransmitter 131 may also provide (e.g., optimize) the coefficients toalso at least partially compensate power amplifier noise from othercomponents of the electronic device 102, such as a power amplifier ofthe wireless transmitter 133. After an uplink period of a time divisionduplexing (TDD) configured radio frame has passed, the wireless receiver135 and/or the wireless receiver 137 may receive wireless signals duringa downlink period of the time division duplexing configured radio frame.For example, the wireless receiver 135 and/or the wireless receiver 137may receive individual signals or a combination of signals (e.g., a MIMOsignal) from the electronic device 110, having transmitted wirelesssignals from the wireless transmitter 111 coupled to the antenna 101and/or from the wireless transmitter 113 coupled to the antenna 103.Power amplifier noise may generally refer to any noise in a signal to betransmitted from an electronic device that may be at least partiallygenerated by one or more power amplifiers of that electronic device.

Electronic devices described herein, such as electronic device 102 andelectronic device 110 shown in FIG. 1 may be implemented using generallyany electronic device for which communication capability is desired. Forexample, electronic device 102 and/or electronic device 110 may beimplemented using a mobile phone, smartwatch, computer (e.g. server,laptop, tablet, desktop), or radio. In some examples, the electronicdevice 102 and/or electronic device 110 may be incorporated into and/orin communication with other apparatuses for which communicationcapability is desired, such as but not limited to, a wearable device, amedical device, an automobile, airplane, helicopter, appliance, tag,camera, or other device.

While not explicitly shown in FIG. 1, electronic device 102 and/orelectronic device 110 may include any of a variety of components in someexamples, including, but not limited to, memory, input/output devices,circuitry, processing units (e.g. processing elements and/orprocessors), or combinations thereof.

The electronic device 102 and the electronic device 110 may each includemultiple antennas. For example, the electronic device 102 and electronicdevice 110 may each have more than two antennas. Three antennas each areshown in FIG. 1, but generally any number of antennas may be usedincluding 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 32, or 64antennas. Other numbers of antennas may be used in other examples. Insome examples, the electronic device 102 and electronic device 110 mayhave a same number of antennas, as shown in FIG. 1. In other examples,the electronic device 102 and electronic device 110 may have differentnumbers of antennas. Generally, systems described herein may includemultiple-input, multiple-output (“MIMO”) systems. MIMO systems generallyrefer to systems including one or more electronic devices which transmittransmissions using multiple antennas and one or more electronic deviceswhich receive transmissions using multiple antennas. In some examples,electronic devices may both transmit and receive transmissions usingmultiple antennas. Some example systems described herein may be “massiveMIMO” systems. Generally, massive MIMO systems refer to systemsemploying greater than a certain number (e.g. 64) antennas to transmitand/or receive transmissions. As the number of antennas increase, so togenerally does the complexity involved in accurately transmitting and/orreceiving transmissions.

Although two electronic devices (e.g. electronic device 102 andelectronic device 110) are shown in FIG. 1, generally the system 100 mayinclude any number of electronic devices.

Electronic devices described herein may include receivers, transmitters,and/or transceivers. For example, the electronic device 102 of FIG. 1includes wireless transmitter 131 and wireless receiver 135, and theelectronic device 110 includes wireless transmitter 111 and wirelessreceiver 115. Generally, receivers may be provided for receivingtransmissions from one or more connected antennas, transmitters may beprovided for transmitting transmissions from one or more connectedantennas, and transceivers may be provided for receiving andtransmitting transmissions from one or more connected antennas. Whileboth electronic devices 102, 110 are depicted in FIG. 1 with individualwireless transmitter and individual wireless receivers, it can beappreciated that a wireless transceiver may be coupled to antennas ofthe electronic device and operate as either a wireless transmitter orwireless receiver, to receive and transmit transmissions. For example, atransceiver of electronic device 102 may be used to providetransmissions to and/or receive transmissions from antenna 121, whileother transceivers of electronic device 110 may be provided to providetransmissions to and/or receive transmissions from antenna 101 andantenna 103. Generally, multiple receivers, transmitters, and/ortransceivers may be provided in an electronic device—one incommunication with each of the antennas of the electronic device. Thetransmissions may be in accordance with any of a variety of protocols,including, but not limited to 5G signals, and/or a variety ofmodulation/demodulation schemes may be used, including, but not limitedto: orthogonal frequency division multiplexing (OFDM), filter bankmulti-carrier (FBMC), the generalized frequency division multiplexing(GFDM), universal filtered multi-carrier (UFMC) transmission, biorthogonal frequency division multiplexing (BFDM), sparse code multipleaccess (SCMA), non-orthogonal multiple access (NOMA), multi-user sharedaccess (MUSA) and faster-than-Nyquist (FTN) signaling withtime-frequency packing. In some examples, the transmissions may be sent,received, or both, in accordance with 5G protocols and/or standards.

Examples of transmitters, receivers, and/or transceivers describedherein, such as the wireless transmitter 131 and the wirelesstransmitter 111 may be implemented using a variety of components,including, hardware, software, firmware, or combinations thereof. Forexample, transceivers, transmitters, or receivers may include circuitryand/or one or more processing units (e.g. processors) and memory encodedwith executable instructions for causing the transceiver to perform oneor more functions described herein (e.g. software).

FIG. 2 is a schematic illustration of an electronic device 200 arrangedin accordance with examples described herein. Electronic device 200includes a baseband transmitter (Tx) 215 and a baseband receiver (Rx)285, each respectively having a transmitter path and a receiver pathto/from transmitting antenna (Tx) 250 and receiving antenna (Rx) 255.Electronic device 200 may represent an implementation of the electronicdevice 102, 110; with the baseband transmitter 215 and transmitter pathrepresenting a wireless transmitter 131, 133 or wireless transmitter111, 113, and with the baseband receiver 285 representing a wirelessreceiver 135, 137 or wireless receiver 115, 117.

After having received a signal to be transmitted t(n) 210, the basebandtransmitter 215 may perform baseband processing on that signal to betransmitted t(n) 210 to generate a baseband signal to be transmittedt(n) 216. The signal 216 is provided to the coefficient calculator 280and also provided, along the transmitter path towards the transmittingantenna 250, to a digital pre-distortion (DPD) filter 220. The DPDfilter 220 at least partially compensates the signal t(n) 216 based on amodel including coefficient data (e.g., a plurality of coefficients)provided to the DPD filter by the coefficient calculator 280. The DPDfilter 220 utilizes the model based on the coefficient data to at leastpartially compensate the signal 216 for noise in the electronic device200, such as nonlinear power amplifier noise generated by the poweramplifier 240. As will be described with respect to the coefficientcalculator 280, the coefficient data may be determined to reduce theerror introduced into the signal to be transmitted t(n) 216 by nonlinearpower amplifier noise, when that signal 216 is amplified by poweramplifier 240 for transmission at the transmitting antenna 250.

After having been at least partially compensated for noise by the DPDfilter 220, the signal to be transmitted t(n) may be further processedalong the transmitter path towards the transmitting antenna 250.Accordingly, the compensated signal 216 is processed by the numericallycontrolled oscillator (NCO) 225, the digital to analog converter 230,the intermediate frequency (IF) filter 235, the mixer 237 in conjunctionwith a provided local oscillating signal from the local oscillator 290,and the power amplifier 240 to generate amplified signal to betransmitted T(n) 247. The signal to be transmitted T(n) 247 is providedto the transmitting antenna 250 via a switch 245. The transmitter pathto the transmitting antenna 250 includes a path through the switch 245for transmission of any signal to be transmitted. That same amplifiedsignal to be transmitted T(n) 247 is provided to the receiver path viathe switch 245, when the switch 245 is activated, as the signal X(n)249.

The switch 245 may be activated by a control signal (e.g., a selectionsignal) that indicates an uplink (TTI) is occurring in a time divisionduplexing configured radio frame that the electronic device 200utilizes. When the switch 245 is activated, the amplified signal to betransmitted T(n) 247 is provided to the receiver path of the electronicdevice 200 to be used as a feedback signal in calculations performed bythe coefficient calculator 280. The amplified signal to be transmittedT(n) 247 is provided to the receiver path as the signal X(n) 249,starting at the low noise amplifier (LNA) 260. The signal X(n) 249 andthe amplified signal to be transmitted T(n) 247 represent the samesignal processed by the power amplifier 240. The signal X(n) 249 and theamplified signal to be transmitted T(n) 247 are both provided by theswitch 245, when the switch 245 is activated, to the receiver path ofthe electronic device 200 and the transmitting antenna 250,respectively. Accordingly, the signal X(n) 249 is processed by the LNA260, the mixer 263 in conjunction with the provided local oscillatingsignal from the local oscillator 290, the intermediate frequency (IF)filter 265, the analog-to-digital converter 270, and the numericallycontrolled oscillator (NCO) 275 to generate the feedback signal X(n) 277that is provided to the coefficient calculator 280. The coefficientcalculator 280 may also receive the control signal indicating that anuplink time period is occurring, and may receive the feedback signalX(n) 277 to process that signal in a calculation to reduce the errorintroduced by the nonlinear power amplifier noise generated by the poweramplifier 240.

After receiving the feedback signal X(n) 277, the coefficient calculator280 may determine to calculate an error signal between the signal to betransmitted t(n) 216 and the compensated wireless transition signal toreduce error in a model of the DPD filter 220. The coefficientcalculator utilizes the error signal to determine and/or updatecoefficient data B(n) 243 (e.g., a plurality of coefficients) providedto the DPD filter 220 for utilization in a model of the DPD filter 220that at least partially compensates non-linear power amplifier noise.For the coefficient calculator 280 to calculate the plurality ofcoefficients, the coefficient calculator 280 may compute an error signalfor reducing a difference between the signal to be transmitted t(n) 216that is input to the DPD filter 220 and the feedback signal X(n) 277.For example, the difference may be reduced (e.g., minimized) byutilizing Equation (1):

$\begin{matrix}{{z(k)} = {\left\lbrack {1 + {\sum\limits_{p = 2}^{P}{\sum\limits_{m = {- M}}^{M}{a_{p,m} \cdot {{y\left( {k - m} \right)}}^{p - 1}}}}} \right\rbrack \cdot {y(k)}}} & (1)\end{matrix}$The signal to be transmitted t(n) 216 may be calculated in Equation (1)as z(k). The feedback signal X(n) 277 may be calculated in Equation (1)as y(k), to be summed over ‘p’ and ‘m,’ where ‘P’ represents thenon-linear order of the power amplifier noise to be compensated and ‘M’represents a “memory” of the coefficient calculator 280. For example,the coefficient calculator may store previous versions of the feedbacksignal X(n) 277, with the ‘m’ term representative of an offset of thefeedback signal X(n) 277, such that the offset indicates a number oftime periods between a received feedback signal X(n) 277 and a previousversion of the feedback signal X(n) 277, received at ‘m’ time periodsbefore the feedback signal X(n) 277 had been received at the coefficientcalculator 280 to perform the calculation. In the example, ‘P’ mayrepresent the number of filter taps for a model of the DPD filter 220 toat least partially compensate a nonlinearity of the power amplifiernoise. In various implementations, ‘P’ may equal 1, 2, 3, 4, 7, 9, 10,12, 16, 20, 100, or 200. Additionally or alternatively, ‘M’ may equal 0,1, 2, 3, 4, 7, 9, 10, 12, 16, 20, 100, or 200. The coefficientcalculator 280 may utilize Equation (1) in conjunction with an algorithmto reduce (e.g., minimize) the difference between z(k) and y(k), such asleast-mean-squares (LMS) algorithm, least-squares (LS) algorithm, ortotal-least-squares (TLS) algorithm. Accordingly, in reducing thedifference between z(k) and y(k), the coefficient calculator determinesthe coefficient data B(n) 243, as the terms a_(p,m) in Equation 1, to beutilized in the DPD filter 220. In some implementations, sample vectorsmay be utilized, instead of the signal to be transmitted t(n) 216, todetermine an initial set of the coefficient data B(n) 243.

In some examples, the coefficient calculator determines the coefficientdata B(n) 243 to be utilized in the DPD filter 220 as a “memoryless”system in which the coefficient data B(n) 243 updates the DPD filter 220with new coefficient data, replacing any coefficient data that the DPDfilter utilized before receiving the coefficient data B(n) 243. Updatingthe DPD filter 220 with the coefficient data B(n) 243 may be referred toas optimizing the coefficient data, with some or all of the coefficientdata being updated. For example, Equation (1) may be reduced to Equation(2) when other versions of the feedback signal X(n) 277 are not utilizedin the calculation, thereby reduced the ‘m’ term to zero, such thatEquation (1) reduces to Equation (2):

$\begin{matrix}{{z(k)} = {\left\lbrack {1 + {\sum\limits_{p = 2}^{P}{a_{p} \cdot {{y(k)}}^{p - 1}}}} \right\rbrack \cdot {y(k)}}} & (2)\end{matrix}$

In utilizing the same receiver path for processing of a received signaland the aforementioned generation of a feedback signal, the electronicdevice 200 may utilize board space and/or resources on a circuitimplementing the electronic device 200, as compared to an electronicdevice that includes a separate path for the feedback signal and aseparate path for processing of a received signal. For example,electronic device 200 utilizes the LNA 260, the mixer 263 in conjunctionwith the provided local oscillating signal from the local oscillator290, the intermediate frequency (IF) filter 265, the analog-to-digitalconverter 270, and the numerically controlled oscillator (NCO) 275 forboth generation of a feedback signal X(n) 277 and for processing of areceived signal R(n) 257. As described, when the switch 245 isactivated, the electronic device 200 utilizes the LNA 260, the mixer 263in conjunction with the provided local oscillating signal from the localoscillator 290, the intermediate frequency (IF) filter 265, theanalog-to-digital converter 270, and the numerically controlledoscillator (NCO) 275 to generate a feedback signal X(n) 277 andcalculates coefficient data with the coefficient calculator 280. Whenthe switch 245 is deactivated, the electronic device 200 utilizes theLNA 260, the mixer 263 in conjunction with the provided localoscillating signal from the local oscillator 290, the intermediatefrequency (IF) filter 265, the analog-to-digital converter 270, and thenumerically controlled oscillator (NCO) 275 to receive and process thereceived signal R(n) 257.

The switch 245 may be deactivated at the end of activation period. Forexample, the control signal that activates the switch 245 may includeinformation that specifies how long the switch 245 is to be activated,e.g., an activation period. The activation period may be the same as anuplink TTI of a time-division duplexing configured radio frame that theelectronic device 200 utilizes. For example, as described with referenceto FIG. 6, the activation period may be a specific uplink TTI thatoperates at a different time period than a downlink TTI. In someexamples, the switch 245 may be activated for the length of the signal216, which may be the same length as the signal 210. Additionally oralternatively, the switch 245 may be deactivated when a wireless signalis detected at the receiving antenna 255. For example, a control signalmay indicate the start of a downlink TTI when a signal is detected atthe receiving antenna 255, which indicates that the activation periodhas finished. Accordingly, the switch 245 may deactivated.

The switch 245 may be deactivated by a control signal that indicates adownlink TTI is occurring in a time division duplexing configured radioframe that the electronic device 200 utilizes. Accordingly, a signalX(n) 249 is not provided to the receiver path of the electronic device200 because the switch 245 is deactivated. With the switch 245deactivated, the received signal R(n) 257 is provided to the receiverpath of the electronic device 200 to processed in the receiver path forthe generation of a baseband received signal 287. The received signalR(n) 257 is provided to the receiver path, starting at the low noiseamplifier (LNA) 260. Accordingly, the received signal R(n) 257 isprocessed by the LNA 260, the mixer 263 in conjunction with the providedlocal oscillating signal from the local oscillator 290, the intermediatefrequency (IF) filter 265, the analog-to-digital converter 270, thenumerically controlled oscillator (NCO) 275, and the baseband receiver285 to generate the baseband received signal 287. In generating thebaseband received signal 287, the electronic device 200 utilizes thesame receiver path that is utilized to generate and provide a feedbacksignal to the coefficient calculator 280, thereby efficiently utilizingthe computational resources and/or board space of the electronic device200. Accordingly, the same receiver path of electronic device 200 isutilized for the receiving wireless signals during downlink time periodsand providing feedback signals to the coefficient calculator duringuplink time periods. In some examples, the coefficient calculator 280,while not being provided a feedback signal X(n) 277 during the downlinktime period, may calculate and/or determine coefficient data while thereceived signal R(n) 257 is being processed. Accordingly, in conjunctionwith time division duplexing configured radio frames, the electronicdevice 200 utilizes a single receiver path to provide both the feedbacksignal X(n) 277 to the coefficient calculator 280 and to receivewireless transmission signals, such as the received signal R(n) 257 toprovide baseband received signals r(n) 287.

FIG. 3 is a schematic illustration of a wireless transmitter 300. Thewireless transmitter 300 receives a data signal 311 and performsoperations to generate wireless communication signals for transmissionvia the antenna 303. The transmitter output data x_(N)(n) 310 isamplified by a power amplifier 332 before the output data aretransmitted on an RF antenna 303. The operations to the RF-front end maygenerally be performed with analog circuitry or processed as a digitalbaseband operation for implementation of a digital front-end. Theoperations of the RF-front end include a scrambler 304, a coder 308, aninterleaver 312, a modulation mapping 316, a frame adaptation 320, anIFFT 324, a guard interval 328, and frequency up-conversion 330.

The scrambler 304 may convert the input data to a pseudo-random orrandom binary sequence. For example, the input data may be a transportlayer source (such as MPEG-2 Transport stream and other data) that isconverted to a Pseudo Random Binary Sequence (PRBS) with a generatorpolynomial. While described in the example of a generator polynomial,various scramblers 304 are possible.

The coder 308 may encode the data outputted from the scrambler to codethe data. For example, a Reed-Solomon (RS) encoder, turbo encoder may beused as a first coder to generate a parity block for each randomizedtransport packet fed by the scrambler 304. In some examples, the lengthof parity block and the transport packet can vary according to variouswireless protocols. The interleaver 312 may interleave the parity blocksoutput by the coder 308, for example, the interleaver 312 may utilizeconvolutional byte interleaving. In some examples, additional coding andinterleaving can be performed after the coder 308 and interleaver 312.For example, additional coding may include a second coder that mayfurther code data output from the interleaver, for example, with apunctured convolutional coding having a certain constraint length.Additional interleaving may include an inner interleaver that formsgroups of joined blocks. While described in the context of a RS coding,turbo coding, and punctured convolution coding, various coders 308 arepossible, such as a low-density parity-check (LDPC) coder or a polarcoder. While described in the context of convolutional byteinterleaving, various interleavers 312 are possible.

The modulation mapping 316 may modulate the data output from theinterleaver 312. For example, quadrature amplitude modulation (QAM) maybe used to map the data by changing (e.g., modulating) the amplitude ofthe related carriers. Various modulation mappings may be used,including, but not limited to: Quadrature Phase Shift Keying(QPSK), SCMANOMA, and MUSA (Multi-user Shared Access). Output from the modulationmapping 316 may be referred to as data symbols. While described in thecontext of QAM modulation, various modulation mappings 316 are possible.The frame adaptation 320 may arrange the output from the modulationmapping according to bit sequences that represent correspondingmodulation symbols, carriers, and frames.

The IFFT 324 may transform symbols that have been framed intosub-carriers (e.g., by frame adaptation 320) into time-domain symbols.Taking an example of a 5G wireless protocol scheme, the IFFT can beapplied as N-point IFFT:

$\begin{matrix}{x_{k} = {\sum\limits_{n = 1}^{N}{X_{n}e^{i\; 2\;\pi\;{{kn}/N}}}}} & (3)\end{matrix}$where X_(n) is the modulated symbol sent in the nth 5G sub-carrier.Accordingly, the output of the IFFT 324 may form time-domain 5G symbols.In some examples, the IFFT 324 may be replaced by a pulse shaping filteror poly-phase filtering banks to output symbols for frequencyup-conversion 330.

In the example of FIG. 3, the guard interval 328 adds a guard intervalto the time-domain 5G symbols. For example, the guard interval may be afractional length of a symbol duration that is added, to reduceinter-symbol interference, by repeating a portion of the end of atime-domain 5G symbol at the beginning of the frame. For example, theguard interval can be a time period corresponding to the cyclic prefixportion of the 5G wireless protocol scheme.

The frequency up-conversion 330 may up-convert the time-domain 5Gsymbols to a specific radio frequency. For example, the time-domain 5Gsymbols can be viewed as a baseband frequency range and a localoscillator can mix the frequency at which it oscillates with the 5Gsymbols to generate 5G symbols at the oscillation frequency. A digitalup-converter (DUC) may also be utilized to convert the time-domain 5Gsymbols.

Accordingly, the 5G symbols can be up-converted to a specific radiofrequency for an RF transmission.

Before transmission, at the antenna 303, a power amplifier 332 mayamplify the transmitter output data x_(N)(n) 310 to output data for anRF transmission in an RF domain at the antenna 303. The antenna 303 maybe an antenna designed to radiate at a specific radio frequency. Forexample, the antenna 303 may radiate at the frequency at which the 5Gsymbols were up-converted. Accordingly, the wireless transmitter 300 maytransmit an RF transmission via the antenna 303 based on the data signal311 received at the scrambler 304. As described above with respect toFIG. 3, the operations of the wireless transmitter 300 can include avariety of processing operations. Such operations can be implemented ina conventional wireless transmitter, with each operation implemented byspecifically-designed hardware for that respective operation. Forexample, a DSP processing unit may be specifically-designed to implementthe IFFT 324. As can be appreciated, additional operations of wirelesstransmitter 300 may be included in a conventional wireless receiver.

The wireless transmitter 300 may be utilized to implement the wirelesstransmitters 111, 113 or wireless transmitters 131, 133 of FIG. 1, forexample. The wireless transmitter 300 may also represent a configurationin which the DPD filter 220 and the coefficient calculator 280 may beutilized. For example, the DPD filter may at least partially compensatethe data signal 311 before providing the data signal 311 to thescrambler 304. A coefficient calculator 280 may be implemented in thewireless transmitter 300, with signal paths to the coefficientcalculator from any element of the transmitter path of the wirelesstransmitter 300.

FIG. 4 is a schematic illustration of wireless receiver 400. Thewireless receiver 400 receives input data X (i,j) 410 from an antenna405 and performs operations of a wireless receiver to generate receiveroutput data at the descrambler 444. The antenna 405 may be an antennadesigned to receive at a specific radio frequency. The operations of thewireless receiver may be performed with analog circuitry or processed asa digital baseband operation for implementation of a digital front-end.The operations of the wireless receiver include a frequencydown-conversion 412, guard interval removal 416, a fast Fouriertransform 420, synchronization 424, channel estimation 428, ademodulation mapping 432, a deinterleaver 436, a decoder 440, and adescrambler 444.

The frequency down-conversion 412 may down-convert the frequency domainsymbols to a baseband processing range. For example, continuing in theexample of a 5G implementation, the frequency-domain 5G symbols may bemixed with a local oscillator frequency to generate 5G symbols at abaseband frequency range. A digital down-converter (DDC) may also beutilized to convert the frequency domain symbols. Accordingly, the RFtransmission including time-domain 5G symbols may be down-converted tobaseband. The guard interval removal 416 may remove a guard intervalfrom the frequency-domain 5G symbols. The FFT 420 may transform thetime-domain 5G symbols into frequency-domain 5G symbols. Taking anexample of a 5G wireless protocol scheme, the FFT can be applied asN-point FFT:

$\begin{matrix}{X_{n} = {\sum\limits_{k = 1}^{N}{x_{k}e^{{- i}\; 2\;\pi\;{{kn}/N}}}}} & (4)\end{matrix}$where X_(n) is the modulated symbol sent in the nth 5G sub-carrier.Accordingly, the output of the FFT 420 may form frequency-domain 5Gsymbols. In some examples, the FFT 420 may be replaced by poly-phasefiltering banks to output symbols for synchronization 424.

The synchronization 424 may detect pilot symbols in the 5G symbols tosynchronize the transmitted data. In some examples of a 5Gimplementation, pilot symbols may be detected at the beginning of aframe (e.g., in a header) in the time-domain. Such symbols can be usedby the wireless receiver 400 for frame synchronization. With the framessynchronized, the 5G symbols proceed to channel estimation 428. Thechannel estimation 428 may also use the time-domain pilot symbols andadditional frequency-domain pilot symbols to estimate the time orfrequency effects (e.g., path loss) to the received signal.

For example, a channel may be estimated according to N signals receivedthrough N antennas (in addition to the antenna 405) in a preamble periodof each signal. In some examples, the channel estimation 428 may alsouse the guard interval that was removed at the guard interval removal416. With the channel estimate processing, the channel estimation 428may at least partially compensate for the frequency-domain 5G symbols bysome factor to reduce the effects of the estimated channel. Whilechannel estimation has been described in terms of time-domain pilotsymbols and frequency-domain pilot symbols, other channel estimationtechniques or systems are possible, such as a MIMO-based channelestimation system or a frequency-domain equalization system.

The demodulation mapping 432 may demodulate the data outputted from thechannel estimation 428. For example, a quadrature amplitude modulation(QAM) demodulator can map the data by changing (e.g., modulating) theamplitude of the related carriers. Any modulation mapping describedherein can have a corresponding demodulation mapping as performed bydemodulation mapping 432. In some examples, the demodulation mapping 432may detect the phase of the carrier signal to facilitate thedemodulation of the 5G symbols. The demodulation mapping 432 maygenerate bit data from the 5G symbols to be further processed by thedeinterleaver 436.

The deinterleaver 436 may deinterleave the data bits, arranged as parityblock from demodulation mapping into a bit stream for the decoder 440,for example, the deinterleaver 436 may perform an inverse operation toconvolutional byte interleaving. The deinterleaver 436 may also use thechannel estimation to at least partially compensate for channel effectsto the parity blocks.

The decoder 440 may decode the data outputted from the scrambler to codethe data. For example, a Reed-Solomon (RS) decoder or turbo decoder maybe used as a decoder to generate a decoded bit stream for thedescrambler 444. For example, a turbo decoder may implement a parallelconcatenated decoding scheme. In some examples, additional decodingand/or deinterleaving may be performed after the decoder 440 anddeinterleaver 436. For example, additional decoding may include anotherdecoder that may further decode data output from the decoder 440. Whiledescribed in the context of a RS decoding and turbo decoding, variousdecoders 440 are possible, such as low-density parity-check (LDPC)decoder or a polar decoder.

The descrambler 444 may convert the output data from decoder 440 from apseudo-random or random binary sequence to original source data. Forexample, the descrambler 44 may convert decoded data to a transportlayer destination (e.g., MPEG-2 transport stream) that is descrambledwith an inverse to the generator polynomial of the scrambler 304. Thedescrambler thus outputs receiver output data. Accordingly, the wirelessreceiver 400 receives an RF transmission including input data X (i,j)410 via to generate the receiver output data.

As described herein, for example with respect to FIG. 4, the operationsof the wireless receiver 400 can include a variety of processingoperations. Such operations can be implemented in a conventionalwireless receiver, with each operation implemented byspecifically-designed hardware for that respective operation. Forexample, a DSP processing unit may be specifically-designed to implementthe FFT 420. As can be appreciated, additional operations of wirelessreceiver 400 may be included in a conventional wireless receiver.

The wireless receiver 400 may be utilized to implement the wirelessreceivers the wireless receivers 115, 117 or wireless receivers 135, 137of FIG. 1, for example. The wireless receiver 400 may also represent aconfiguration in which the coefficient calculator 280 may be utilized.For example, wireless receiver 400 may provide a feedback signal to acoefficient calculator 280 after descrambling the feedback signal at thedescrambler 444. Accordingly, a coefficient calculator 280 may beimplemented in the wireless receiver 400 with a signal path to thecoefficient calculator from the receiver path of the wireless receiver400.

FIG. 5 is a block diagram of a processing unit 550, which may beimplemented as a coefficient calculator 280, in accordance with examplesdescribed herein. The processing unit 550 may receive input data (e.g. X(i,j)) 560 a-c from such a computing system, such as t(n) 216 and/orX(n) 277. For example, if the input data 560 a-c corresponds to afeedback signal, such as the feedback signal X(n) 277, the processingunit 550 may retrieve from memory 580, either a signal to be transmittedt(n) 210 or previous versions of the feedback signal, such as previouslyreceived feedback signals X(n) 277. The previously received feedbacksignals X(n) 277 may have been received at a different time period thanthe feedback signal X(n) 277 received during a current uplink timeperiod. For example, the other feedback signals X(n) 277 stored inmemory may have been received during previous uplink time periods beforethe current uplink time period.

Additionally or alternatively, the currently received feedback signalX(n) 277 may be stored in the memory 580 to be accessed by theprocessing unit 550 (e.g., coefficient calculator) for calculation ofcoefficient data. For example, the currently received feedback signalX(n) 277 may be stored in memory 580 during the current uplink timeperiod, to be later calculated by the processing unit 550 during adownlink time period or another time period.

The processing unit 550 may include multiplication unit/accumulationunits 562 a-c, 566 a-c and memory lookup units 564 a-c, 568 a-c that,that may generate output data (e.g. B (u,v)) 570 a-c. The output data B(u,v)) 570 a-c may be provided, for example in electronic device 200, asthe coefficient data B(n) 243 to the DPD filter 220 for utilization in amodel of the DPD filter 220 that at least partially compensatesnon-linear power amplifier noise. The processing unit 550, may beprovided instructions that cause the processing unit 550 to configurethe multiplication units 562 a-c to multiply input data 560 a-c withcoefficient data and accumulation units 566 a-c to accumulate processingresults to generate the output data 570 a-c, and thus provided as thecoefficient data B(n) 243.

The multiplication unit/accumulation units 562 a-c, 566 a-c multiply twooperands from the input data 560 a-c to generate a multiplicationprocessing result that is accumulated by the accumulation unit portionof the multiplication unit/accumulation units 562 a-c, 566 a-c. Themultiplication unit/accumulation units 562 a-c, 566 a-c adds themultiplication processing result to update the processing result storedin the accumulation unit portion, thereby accumulating themultiplication processing result. For example, the multiplicationunit/accumulation units 562 a-c, 566 a-c may perform amultiply-accumulate operation such that two operands, M and N, aremultiplied and then added with P to generate a new version of P that isstored in its respective multiplication unit/accumulation units. Thememory look-up units 564 a-c, 568 a-c retrieve data stored in memory580. For example, the memory look-up unit can be a table look-up thatretrieves a specific coefficient of additional coefficient data storedin the memory 580. For example, the memory 580 may additionally storepreviously calculated versions of the coefficient data B(n) 243. Theoutput of the memory look-up units 564 a-c, 568 a-c is provided to themultiplication unit/accumulation units 562 a-c, 566 a c that may beutilized as a multiplication operand in the multiplication unit portionof the multiplication unit/accumulation units 562 a-c, 566 a-c. Usingsuch a circuitry arrangement, the output data (e.g. B (u,v)) 570 a-c maybe generated from the input data (e.g. X (i,j)) 560 a-c.

In some examples, coefficient data, for example from memory 580, can bemixed with the input data X (i,j) 560 a-c to generate the output data B(u,v) 570 a-c. The relationship of the coefficient data to the outputdata B (u,v) 570 a-c based on the input data X (i,j) 560 a-c may beexpressed as:

$\begin{matrix}{{B\left( {u,v} \right)} = {f\left( {\sum\limits_{m,n}^{M,N}{a_{m,n}^{''}{f\left( {\sum\limits_{k,l}^{K,L}{a_{k,l}^{\prime}{X\left( {{i + k},{j + l}} \right)}}} \right)}}} \right)}} & (5)\end{matrix}$where a_(k,l)′, a_(m,n)″ are coefficients for the first set ofmultiplication/accumulation units 562 a-c and second set ofmultiplication/accumulation units 566 a-c, respectively, and where f(•)stands for the mapping relationship performed by the memory look-upunits 564 a-c, 568 a-c. As described above, the memory look-up units 564a-c, 568 a-c retrieve previously calculated coefficient data (e.g.,previous version of the coefficient data B(n) 243) to mix with the inputdata. Accordingly, the output data may be provided by manipulating theinput data with multiplication/accumulation units using coefficient datastored in the memory 580. The resulting mapped data may be manipulatedby additional multiplication/accumulation units using additional sets ofcoefficients stored in the memory associated with the desired wirelessprotocol.

Further, it can be shown that the system 500, as represented by Equation(5), may approximate any nonlinear mapping with arbitrarily small errorin some examples and the mapping of system 500 is determined by thecoefficients a_(k,l)′, a_(m,n)″. For example, if such coefficient datais specified, any mapping and processing between the input data X (i,j)560 a-c and the output data B (u,v) 570 a-c may be accomplished by thesystem 500. Such a relationship, as derived from the circuitryarrangement depicted in system 500, may be used to train an entity ofthe computing system 500 to generate coefficient data. For example,using Equation (5), an entity of the computing system 500 may compareinput data to the output data to generate the coefficient data.

In the example of system 500, the processing unit 550 mixes thecoefficient data with the input data X (i,j) 560 a-c utilizing thememory look-up units 564 a-c, 568 a-c. In some examples, the memorylook-up units 564 a-c, 568 a-c can be referred to as table look-upunits. The coefficient data may be associated with a mappingrelationship for the input data X (i,j) 560 a-c to the output data B(u,v) 570 a-c. For example, the coefficient data may representnon-linear mappings of the input data X (i,j) 560 a-c to the output dataB (u,v) 570 a-c. In some examples, the non-linear mappings of thecoefficient data may represent a Gaussian function, a piece-wise linearfunction, a sigmoid function, a thin-plate-spline function, amulti-quadratic function, a cubic approximation, an inversemulti-quadratic function, or combinations thereof. In some examples,some or all of the memory look-up units 564 a-c, 568 a-c may bedeactivated. For example, one or more of the memory look-up units 564a-c, 568 a-c may operate as a gain unit with the unity gain.

Each of the multiplication unit/accumulation units 562 a-c, 566 a-c mayinclude multiple multipliers, multiple accumulation unit, or and/ormultiple adders. Any one of the multiplication unit/accumulation units562 a-c, 566 a may be implemented using an ALU. In some examples, anyone of the multiplication unit/accumulation units 562 a-c, 566 a-c caninclude one multiplier and one adder that each perform, respectively,multiple multiplications and multiple additions. The input-outputrelationship of a multiplication/accumulation unit 562, 566 may berepresented as:

$B_{out} = {\sum\limits_{i = 1}^{I}{C_{i}*{B_{i\; n}(i)}}}$where “I” represents a number to perform the multiplications in thatunit, C_(i) the coefficients which may be accessed from a memory, suchas memory 580, and B_(in)(i) represents a factor from either the inputdata X (i,j) 560 a-c or an output from multiplication unit/accumulationunits 562 a-c, 566 a-c. In an example, the output of a set ofmultiplication unit/accumulation units, B_(out), equals the sum ofcoefficient data, C_(i) multiplied by the output of another set ofmultiplication unit/accumulation units, B_(in)(i). B_(in)(i) may also bethe input data such that the output of a set of multiplicationunit/accumulation units, B_(out), equals the sum of coefficient data,C_(i) multiplied by input data.

While described above as the processing unit 550 implementing acoefficient calculator 280, additionally or alternatively, thecoefficient calculator 280 can be implemented using one or moreprocessing units (e.g., processing unit(s) 550), for example, having anynumber of cores. In various implementations, processing units caninclude an arithmetic logic unit (ALU), a bit manipulation unit, amultiplication unit, an accumulation unit, an adder unit, a look-uptable unit, a memory look-up unit, or any combination thereof. Forexample, the processing unit 550 includes multiplication units,accumulation units, and, memory look-up units.

FIG. 6 is a schematic illustration of a time frame 600 for a TDDtransmission time interval (TTI) arranged in accordance with examplesdescribed herein. The time frame 600 includes downlink TTIs 601, 604,and 605. The time frame also includes uplink TTIs 603. The time frame600 also includes special time frames 602, which may include additionaluplink and/or downlink TTIs for special TDD time periods. For example, aspecial time period may be allocated in the time frame 600 for specificfunctionalities of a wireless protocol, such as signaling/handshaking.The downlink TTIs may be of varying time period lengths, as depicted,with the downlink TTI 604 being thrice as long as the downlink TTI 601.

The time frame 600 may be utilized in time-division duplexing configuredradio frames for electronic devices described herein. For example, withrespect to the electronic device 200, the switch 245 activates a path toprovide the feedback signal X(n) 277 through the wireless receiver pathto the coefficient calculator 280, when the wireless receiver path isnot receiving an active wireless signal. For example, the wirelessreceiver path may not receive an active wireless signal during theuplink TTIs 603. Accordingly, during the uplink TTIs 603, the switch 245may be activated to provide the feedback signal X(n) 277 through thewireless receiver path to the coefficient calculator 280. In providingthe feedback over multiple uplink TTIs 603, the coefficient calculator280 may provide the coefficients of a model that at least partiallycompensate for nonlinear power amplifier noise. Additionally oralternatively, during at least a portion of downlink TTIs 601, 604, and605, the switch may deactivate the path that provides feedback signalX(n) 277 through the wireless receiver path, so that the wirelessreceiver portion of a wireless transceiver may receive wirelesstransmission signals R(n) 257, thereby providing for efficient TDDconfigured radio frames to both provide the feedback signal X(n) 277 tothe coefficient calculator 280 and to receive wireless signals R(n) 257using the same wireless receiver path.

FIG. 7 is a schematic illustration of a full duplex compensation method700 in accordance with examples described herein. Example method 700 maybe implemented using, for example, electronic device 102, 110 of FIG. 1,electronic device 200 of FIG. 2, processing unit 550 of FIG. 5, or anysystem or combination of the systems depicted in the Figures describedherein, such as in conjunction with a time frame 600 of FIG. 6. Theoperations described in blocks 708-728 may also be stored ascomputer-executable instructions in a computer-readable medium.

Example method 700 may begin with block 708 that starts execution of thepower amplifier noise compensation method and includes providing aninput signal to be transmitted at a transmitter to a receiver via a paththat couples the transmitter and the receiver. In the example, atransmitter and receiver may be included in wireless transceiver withpaths from respective transmitting and receiving antennas, such as theelectronic device 200. In context of FIG. 2, the signal to betransmitted T(n) 247 is provided to the transmitting antenna 250 via aswitch 245. The transmitter path to the transmitting antenna 250includes a path through the switch 245 for transmission of any signal tobe transmitted. That same amplified signal to be transmitted T(n) 247 isprovided to the receiver path via the switch 245, when the switch 245 isactivated, as the signal X(n) 249. Block 708 may be followed by block712, such that the method further includes providing, after processingthrough the receiver, a feedback signal based on the input signal to betransmitted to the coefficient calculator. In the context of FIG. 2,after processing of the signal X(n) 249, a feedback signal X(n) 277 isprovided to the coefficient calculator 280.

Block 712 may be followed by block 716, such that the method furtherincludes calculating an error representative of power amplifier noisebased partly on the input signal to be transmitted and the feedbacksignal to generate coefficient data associated with the power amplifiernoise. For example, various ALUs, such as multiplication units, in anintegrated circuit may be configured to operate as the circuitry of FIG.5, thereby combining the input signal to be transmitted and the feedbacksignal to generate and/or update a plurality of coefficients to beutilized in DPD filter as a model for at least partially compensatingnon-linear power amplifier noise. Block 716 may be followed by block720, such that the method further includes deactivating the path thatcouples the transmitter and the receiver. In the context of FIG. 2, theswitch 245 deactivates the path that provides between the transmitterand the receiver that provides the amplified signal to be transmittedX(n) 249 to wireless receiver path. In deactivating that path, thewireless receiver portion of a wireless transceiver may receive wirelesstransmission signals, thereby providing for efficient TDD configuredradio frames.

Block 720 may be followed by a block 724, such that the method furtherincludes receiving, at a radio frequency (RF) antenna, an additionalsignal to be transmitted. With the switch 245 deactivated, theelectronic device 200 utilizes the LNA 260, the mixer 263 in conjunctionwith the provided local oscillating signal from the local oscillator290, the intermediate frequency (IF) filter 265, the analog-to-digitalconverter 270, and the numerically controlled oscillator (NCO) 275 toreceive and process one or more received signals R(n) 257. Block 724 maybe followed by block 728 that ends the example method 700.

The blocks included in the described example method 700 is forillustration purposes. In some embodiments, these blocks may beperformed in a different order. In some other embodiments, variousblocks may be eliminated. In still other embodiments, various blocks maybe divided into additional blocks, supplemented with other blocks, orcombined together into fewer blocks. Other variations of these specificblocks are contemplated, including changes in the order of the blocks,changes in the content of the blocks being split or combined into otherblocks, etc.

FIG. 8 is a block diagram of an electronic device 800 arranged inaccordance with examples described herein. The electronic device 800 mayoperate in accordance with any example described herein, such aselectronic device 102, 110 of FIG. 1, electronic device 200 of FIG. 2,processing unit 550 of FIG. 5, or any system or combination of thesystems depicted in the Figures described herein, such as in conjunctionwith a time frame 600 of FIG. 6. The electronic device 800 may beimplemented in a smartphone, a wearable electronic device, a server, acomputer, an appliance, a vehicle, or any type of electronic device. Theelectronic device 800 includes a computing system 802, a coefficientcalculator 840, an I/O interface 870, and a network interface 890coupled to a network 895. The computing system 802 includes a wirelesstransceiver 810. The wireless transceiver may include a wirelesstransmitter and/or wireless receiver, such as wireless transmitter 300and wireless receiver 400. Coefficient calculator 840 may include anytype of microprocessor, central processing unit (CPU), an applicationspecific integrated circuits (ASIC), a digital signal processor (DSP)implemented as part of a field-programmable gate array (FPGA), asystem-on-chip (SoC), or other hardware to provide processing for device800.

The computing system 802 includes memory units 850 (e.g., memory look-upunit), which may be non-transitory hardware readable medium includinginstructions, respectively, for calculating coefficient or be memoryunits for the retrieval, calculation, or storage of signals to becompensated based on calculated coefficient data. The coefficientcalculator 840 may control the computing system 802 with controlinstructions that indicate when to execute such stored instructions forcalculating coefficient or for the retrieval or storage of signals to becompensated based on calculated coefficient. Upon receiving such controlinstructions, the wireless transceiver 810 may execute suchinstructions. For example, such instructions may include a program thatexecutes the method 700. Communications between the coefficientcalculator 840, the I/O interface 870, and the network interface 890 areprovided via an internal bus 880. The coefficient calculator 840 mayreceive control instructions from the I/O interface 870 or the networkinterface 890, such as instructions to calculate an autocorrelationmatrix.

Bus 880 may include one or more physical buses, communicationlines/interfaces, and/or point-to-point connections, such as PeripheralComponent Interconnect (PCI) bus, a Gen-Z switch, a CCIX interface, orthe like. The I/O interface 870 can include various user interfacesincluding video and/or audio interfaces for the user, such as a tabletdisplay with a microphone. Network interface 890 communications withother electronic devices, such as electronic device 800 or acloud-electronic server, over the network 895. For example, the networkinterface 890 may be a USB interface.

FIG. 9 illustrates an example of a wireless communications system 900 inaccordance with aspects of the present disclosure. The wirelesscommunications system 900 includes a base station 910, a mobile device915, a drone 917, a small cell 930, and vehicles 940, 945. The basestation 910 and small cell 930 may be connected to a network thatprovides access to the Internet and traditional communication links. Thesystem 900 may facilitate a wide-range of wireless communicationsconnections in a 5G system that may include various frequency bands,including but not limited to: a sub-6 GHz band (e.g., 700 MHzcommunication frequency), mid-range communication bands (e.g., 2.4 GHz),mmWave bands (e.g., 24 GHz), and a NR band (e.g., 3.5 GHz).

Additionally or alternatively, the wireless communications connectionsmay support various modulation schemes, including but not limited to:filter bank multi-carrier (FBMC), the generalized frequency divisionmultiplexing (GFDM), universal filtered multi-carrier (UFMC)transmission, bi-orthogonal frequency division multiplexing (BFDM),sparse code multiple access (SCMA), non-orthogonal multiple access(NOMA), multi-user shared access (MUSA), and faster-than-Nyquist (FTN)signaling with time-frequency packing. Such frequency bands andmodulation techniques may be a part of a standards framework, such asLong Term Evolution (LTE) (e.g., 1.8 GHz band) or other technicalspecification published by an organization like 3GPP or IEEE, which mayinclude various specifications for subcarrier frequency ranges, a numberof subcarriers, uplink/downlink transmission speeds, TDD/FDD, and/orother aspects of wireless communication protocols.

The system 900 may depict aspects of a radio access network (RAN), andsystem 900 may be in communication with or include a core network (notshown). The core network may include one or more serving gateways,mobility management entities, home subscriber servers, and packet datagateways. The core network may facilitate user and control plane linksto mobile devices via the RAN, and it may be an interface to an externalnetwork (e.g., the Internet). Base stations 910, communication devices920, and small cells 930 may be coupled with the core network or withone another, or both, via wired or wireless backhaul links (e.g., S1interface, X2 interface, etc.).

The system 900 may provide communication links connected to devices or“things,” such as sensor devices, e.g., solar cells 937, to provide anInternet of Things (“IoT”) framework. Connected things within the IoTmay operate within frequency bands licensed to and controlled bycellular network service providers, or such devices or things may. Suchfrequency bands and operation may be referred to as narrowband IoT(NB-IoT) because the frequency bands allocated for IoT operation may besmall or narrow relative to the overall system bandwidth. Frequencybands allocated for NB-IoT may have bandwidths of, 50, 100, 150, or 200kHz, for example.

Additionally or alternatively, the IoT may include devices or thingsoperating at different frequencies than traditional cellular technologyto facilitate use of the wireless spectrum. For example, an IoTframework may allow multiple devices in system 900 to operate at a sub-6GHz band or other industrial, scientific, and medical (ISM) radio bandswhere devices may operate on a shared spectrum for unlicensed uses. Thesub-6 GHz band may also be characterized as and may also becharacterized as an NB-IoT band. For example, in operating at lowfrequency ranges, devices providing sensor data for “things,” such assolar cells 937, may utilize less energy, resulting in power-efficiencyand may utilize less complex signaling frameworks, such that devices maytransmit asynchronously on that sub-6 GHz band. The sub-6 GHz band maysupport a wide variety of uses case, including the communication ofsensor data from various sensors devices. Examples of sensor devicesinclude sensors for detecting energy, heat, light, vibration, biologicalsignals (e.g., pulse, EEG, EKG, heart rate, respiratory rate, bloodpressure), distance, speed, acceleration, or combinations thereof.Sensor devices may be deployed on buildings, individuals, and/or inother locations in the environment. The sensor devices may communicatewith one another and with computing systems which may aggregate and/oranalyze the data provided from one or multiple sensor devices in theenvironment.

In such a 5G framework, devices may perform functionalities performed bybase stations in other mobile networks (e.g., UMTS or LTE), such asforming a connection or managing mobility operations between nodes(e.g., handoff or reselection). For example, mobile device 915 mayreceive sensor data from the user utilizing the mobile device 915, suchas blood pressure data, and may transmit that sensor data on anarrowband IoT frequency band to base station 910. In such an example,some parameters for the determination by the mobile device 915 mayinclude availability of licensed spectrum, availability of unlicensedspectrum, and/or time-sensitive nature of sensor data. Continuing in theexample, mobile device 915 may transmit the blood pressure data becausea narrowband IoT band is available and can transmit the sensor dataquickly, identifying a time-sensitive component to the blood pressure(e.g., if the blood pressure measurement is dangerously high or low,such as systolic blood pressure is three standard deviations from norm).

Additionally or alternatively, mobile device 915 may formdevice-to-device (D2D) connections with other mobile devices or otherelements of the system 900. For example, the mobile device 915 may formRFID, WiFi, MultiFire, Bluetooth, or Zigbee connections with otherdevices, including communication device 920 or vehicle 945. In someexamples, D2D connections may be made using licensed spectrum bands, andsuch connections may be managed by a cellular network or serviceprovider. Accordingly, while the above example was described in thecontext of narrowband IoT, it can be appreciated that otherdevice-to-device connections may be utilized by mobile device 915 toprovide information (e.g., sensor data) collected on different frequencybands than a frequency band determined by mobile device 915 fortransmission of that information.

Moreover, some communication devices may facilitate ad-hoc networks, forexample, a network being formed with communication devices 920 attachedto stationary objects and the vehicles 940, 945, without a traditionalconnection to a base station 910 and/or a core network necessarily beingformed. Other stationary objects may be used to support communicationdevices 920, such as, but not limited to, trees, plants, posts,buildings, blimps, dirigibles, balloons, street signs, mailboxes, orcombinations thereof. In such a system 900, communication devices 920and small cell 930 (e.g., a small cell, femtocell, WLAN access point,cellular hotspot, etc.) may be mounted upon or adhered to anotherstructure, such as lampposts and buildings to facilitate the formationof ad-hoc networks and other IoT-based networks. Such networks mayoperate at different frequency bands than existing technologies, such asmobile device 915 communicating with base station 910 on a cellularcommunication band.

The communication devices 920 may form wireless networks, operating ineither a hierarchal or ad-hoc network fashion, depending, in part, onthe connection to another element of the system 900. For example, thecommunication devices 920 may utilize a 700 MHz communication frequencyto form a connection with the mobile device 915 in an unlicensedspectrum, while utilizing a licensed spectrum communication frequency toform another connection with the vehicle 945. Communication devices 920may communicate with vehicle 945 on a licensed spectrum to providedirect access for time-sensitive data, for example, data for anautonomous driving capability of the vehicle 945 on a 5.9 GHz band ofDedicated Short Range Communications (DSRC).

Vehicles 940 and 945 may form an ad-hoc network at a different frequencyband than the connection between the communication device 920 and thevehicle 945. For example, for a high bandwidth connection to providetime-sensitive data between vehicles 940, 945, a 24 GHz mmWave band maybe utilized for transmissions of data between vehicles 940, 945. Forexample, vehicles 940, 945 may share real-time directional andnavigation data with each other over the connection while the vehicles940, 945 pass each other across a narrow intersection line. Each vehicle940, 945 may be tracking the intersection line and providing image datato an image processing algorithm to facilitate autonomous navigation ofeach vehicle while each travels along the intersection line. In someexamples, this real-time data may also be substantially simultaneouslyshared over an exclusive, licensed spectrum connection between thecommunication device 920 and the vehicle 945, for example, forprocessing of image data received at both vehicle 945 and vehicle 940,as transmitted by the vehicle 940 to vehicle 945 over the 24 GHz mmWaveband. While shown as automobiles in FIG. 9, other vehicles may be usedincluding, but not limited to, aircraft, spacecraft, balloons, blimps,dirigibles, trains, submarines, boats, ferries, cruise ships,helicopters, motorcycles, bicycles, drones, or combinations thereof.

While described in the context of a 24 GHz mmWave band, it can beappreciated that connections may be formed in the system 900 in othermmWave bands or other frequency bands, such as 28 GHz, 37 GHz, 38 GHz,39 GHz, which may be licensed or unlicensed bands. In some cases,vehicles 940, 945 may share the frequency band that they arecommunicating on with other vehicles in a different network. Forexample, a fleet of vehicles may pass vehicle 940 and, temporarily,share the 24 GHz mmWave band to form connections among that fleet, inaddition to the 24 GHz mmWave connection between vehicles 940, 945. Asanother example, communication device 920 may substantiallysimultaneously maintain a 700 MHz connection with the mobile device 915operated by a user (e.g., a pedestrian walking along the street) toprovide information regarding a location of the user to the vehicle 945over the 5.9 GHz band. In providing such information, communicationdevice 920 may leverage antenna diversity schemes as part of a massiveMIMO framework to facilitate time-sensitive, separate connections withboth the mobile device 915 and the vehicle 945. A massive MIMO frameworkmay involve a transmitting and/or receiving devices with a large numberof antennas (e.g., 12, 20, 64, 128, etc.), which may facilitate precisebeamforming or spatial diversity unattainable with devices operatingwith fewer antennas according to legacy protocols (e.g., WiFi or LTE).

The base station 910 and small cell 930 may wirelessly communicate withdevices in the system 900 or other communication-capable devices in thesystem 900 having at the least a sensor wireless network, such as solarcells 937 that may operate on an active/sleep cycle, and/or one or moreother sensor devices. The base station 910 may provide wirelesscommunications coverage for devices that enter its coverages area, suchas the mobile device 915 and the drone 917. The small cell 930 mayprovide wireless communications coverage for devices that enter itscoverage area, such as near the building that the small cell 930 ismounted upon, such as vehicle 945 and drone 917.

Generally, a small cell 930 may be referred to as a small cell andprovide coverage for a local geographic region, for example, coverage of200 meters or less in some examples. This may contrasted with atmacrocell, which may provide coverage over a wide or large area on theorder of several square miles or kilometers. In some examples, a smallcell 930 may be deployed (e.g., mounted on a building) within somecoverage areas of a base station 910 (e.g., a macrocell) where wirelesscommunications traffic may be dense according to a traffic analysis ofthat coverage area. For example, a small cell 930 may be deployed on thebuilding in FIG. 9 in the coverage area of the base station 910 if thebase station 910 generally receives and/or transmits a higher amount ofwireless communication transmissions than other coverage areas of thatbase station 910. A base station 910 may be deployed in a geographicarea to provide wireless coverage for portions of that geographic area.As wireless communications traffic becomes more dense, additional basestations 910 may be deployed in certain areas, which may alter thecoverage area of an existing base station 910, or other support stationsmay be deployed, such as a small cell 930. Small cell 930 may be afemtocell, which may provide coverage for an area smaller than a smallcell (e.g., 100 meters or less in some examples (e.g., one story of abuilding)).

While base station 910 and small cell 930 may provide communicationcoverage for a portion of the geographical area surrounding theirrespective areas, both may change aspects of their coverage tofacilitate faster wireless connections for certain devices. For example,the small cell 930 may primarily provide coverage for devicessurrounding or in the building upon which the small cell 930 is mounted.However, the small cell 930 may also detect that a device has entered iscoverage area and adjust its coverage area to facilitate a fasterconnection to that device.

For example, a small cell 930 may support a massive MIMO connection withthe drone 917, which may also be referred to as an unmanned aerialvehicle (UAV), and, when the vehicle 945 enters it coverage area, thesmall cell 930 adjusts some antennas to point directionally in adirection of the vehicle 945, rather than the drone 917, to facilitate amassive MIMO connection with the vehicle, in addition to the drone 917.In adjusting some of the antennas, the small cell 930 may not support asfast as a connection to the drone 917 at a certain frequency, as it hadbefore the adjustment. For example, the small cell 930 may becommunicating with the drone 917 on a first frequency of variouspossible frequencies in a 4G LTE band of 1.8 GHz. However, the drone 917may also request a connection at a different frequency with anotherdevice (e.g., base station 910) in its coverage area that may facilitatea similar connection as described with reference to the small cell 930,or a different (e.g., faster, more reliable) connection with the basestation 910, for example, at a 3.5 GHz frequency in the 5G NR band. Insome examples, drone 917 may serve as a movable or aerial base station.Accordingly, the system 900 may enhance existing communication links incompensating, at least partially, non-linear power amplifier devices fordevices that include power amplifiers, for example, in both the 4GE LTEand 5G NR bands.

The wireless communications system 900 may include devices such as basestation 910, communication device 920, and small cell 930 that maysupport several connections at varying frequencies to devices in thesystem 900, while also at least partially compensating for non-linearpower amplifier noise utilizing coefficient calculators, such ascoefficient calculator 280. Such devices may operate in a hierarchalmode or an ad-hoc mode with other devices in the network of system 900.While described in the context of a base station 910, communicationdevice 920, and small cell 930, it can be appreciated that other devicesthat can support several connections with devices in the network, whilealso at least partially compensating for non-linear power amplifiernoise utilizing coefficient calculators, may be included in system 900,including but not limited to: macrocells, femtocells, routers,satellites, and RFID detectors.

In various examples, the elements of wireless communication system 900,such as base station 910, a mobile device 915, a drone 917,communication device 920, a small cell 930, and vehicles 940, 945, maybe implemented as an electronic device described herein that at leastpartially compensate for non-linear power amplifier noise utilizingcoefficient calculators. For example, the communication device 920 maybe implemented as electronic devices described herein, such aselectronic device 102, 110 of FIG. 1, electronic device 200 of FIG. 2,processing unit 550 of FIG. 5, or any system or combination of thesystems depicted in the Figures described herein, such as in conjunctionwith a time frame 600 of FIG. 6.

FIG. 10 illustrates an example of a wireless communications system 1000in accordance with aspects of the present disclosure. The wirelesscommunications system 1000 includes a mobile device 1015, a drone 1017,a communication device 1020, and a small cell 1030. A building 1010 alsoincludes devices of the wireless communication system 1000 that may beconfigured to communicate with other elements in the building 1010 orthe small cell 1030. The building 1010 includes networked workstations1040, 1045, virtual reality device 1050, IoT devices 1055, 1060, andnetworked entertainment device 1065. In the depicted system 1000, IoTdevices 1055, 1060 may be a washer and dryer, respectively, forresidential use, being controlled by the virtual reality device 1050.Accordingly, while the user of the virtual reality device 1050 may be indifferent room of the building 1010, the user may control an operationof the IoT device 1055, such as configuring a washing machine setting.Virtual reality device 1050 may also control the networked entertainmentdevice 1065. For example, virtual reality device 1050 may broadcast avirtual game being played by a user of the virtual reality device 1050onto a display of the networked entertainment device 1065.

The small cell 1030 or any of the devices of building 1010 may beconnected to a network that provides access to the Internet andtraditional communication links. Like the system 900, the system 1000may facilitate a wide-range of wireless communications connections in a5G system that may include various frequency bands, including but notlimited to: a sub-6 GHz band (e.g., 700 MHz communication frequency),mid-range communication bands (e.g., 2.4 GHz), mmWave bands (e.g., 24GHz), or any other bands, such as a 1 MHz, 5 MHz, 10 MHz, 20 MHz band.Additionally or alternatively, the wireless communications connectionsmay support various modulation schemes as described above with referenceto system 900. System 1000 may operate and be configured to communicateanalogously to system 900. Accordingly, similarly numbered elements ofsystem 1000 and system 900 may be configured in an analogous way, suchas communication device 920 to communication device 1020, small cell 930to small cell 1030, etc.

Like the system 900, where elements of system 900 are configured to formindependent hierarchal or ad-hoc networks, communication device 1020 mayform a hierarchal network with small cell 1030 and mobile device 1015,while an additional ad-hoc network may be formed among the small cell1030 network that includes drone 1017 and some of the devices of thebuilding 1010, such as networked workstations 1040, 1045 and IoT devices1055, 1060.

Devices in communication system 1000 may also form (D2D) connectionswith other mobile devices or other elements of the system 1000. Forexample, the virtual reality device 1050 may form a narrowband IoTconnections with other devices, including IoT device 1055 and networkedentertainment device 1065. As described above, in some examples, D2Dconnections may be made using licensed spectrum bands, and suchconnections may be managed by a cellular network or service provider.Accordingly, while the above example was described in the context of anarrowband IoT, it can be appreciated that other device-to-deviceconnections may be utilized by virtual reality device 1050.

In various examples, the elements of wireless communication system 1000,such as the mobile device 1015, the drone 1017, the communication device1020, and the small cell 1030, the networked workstations 1040, 1045,the virtual reality device 1050, the IoT devices 1055, 1060, and thenetworked entertainment device 1065, may be implemented as electronicdevices described herein that at least partially compensate fornon-linear power amplifier noise utilizing coefficient calculators. Forexample, the communication device 1020 may be implemented as electronicdevices described herein, such as electronic device 102, 110 of FIG. 1,electronic device 200 of FIG. 2, processing unit 550 of FIG. 5, or anysystem or combination of the systems depicted in the Figures describedherein, such as in conjunction with a time frame 600 of FIG. 6.

Certain details are set forth above to provide a sufficientunderstanding of described examples. However, it will be clear to oneskilled in the art that examples may be practiced without various ofthese particular details. The description herein, in connection with theappended drawings, describes example configurations and does notrepresent all the examples that may be implemented or that are withinthe scope of the claims. The terms “exemplary” and “example” as may beused herein means “serving as an example, instance, or illustration,”and not “preferred” or “advantageous over other examples.” The detaileddescription includes specific details for the purpose of providing anunderstanding of the described techniques. These techniques, however,may be practiced without these specific details. In some instances,well-known structures and devices are shown in block diagram form inorder to avoid obscuring the concepts of the described examples.

Information and signals described herein may be represented using any ofa variety of different technologies and techniques. For example, data,instructions, commands, information, signals, bits, symbols, and chipsthat may be referenced throughout the above description may berepresented by voltages, currents, electromagnetic waves, magneticfields or particles, optical fields or particles, or any combinationthereof.

Techniques described herein may be used for various wirelesscommunications systems, which may include multiple access cellularcommunication systems, and which may employ code division multipleaccess (CDMA), time division multiple access (TDMA), frequency divisionmultiple access (FDMA), orthogonal frequency division multiple access(OFDMA), or single carrier frequency division multiple access (SC-FDMA),or any a combination of such techniques. Some of these techniques havebeen adopted in or relate to standardized wireless communicationprotocols by organizations such as Third Generation Partnership Project(3GPP), Third Generation Partnership Project 2 (3GPP2) and IEEE. Thesewireless standards include Ultra Mobile Broadband (UMB), UniversalMobile Telecommunications System (UMTS), Long Term Evolution (LTE),LTE-Advanced (LTE-A), LTE-A Pro, New Radio (NR), IEEE 802.11 (WiFi), andIEEE 802.16 (WiMAX), among others.

The terms “5G” or “5G communications system” may refer to systems thatoperate according to standardized protocols developed or discussedafter, for example, LTE Releases 13 or 14 or WiMAX 802.16e-2005 by theirrespective sponsoring organizations. The features described herein maybe employed in systems configured according to other generations ofwireless communication systems, including those configured according tothe standards described above.

The various illustrative blocks and modules described in connection withthe disclosure herein may be implemented or performed with ageneral-purpose processor, a digital signal processor (DSP), anapplication-specific integrated circuit (ASIC), a field-programmablegate array (FPGA), or other programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described herein. Ageneral-purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices (e.g., a combinationof a DSP and a microprocessor, multiple microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration).

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions may bestored on or transmitted over as one or more instructions or code on acomputer-readable medium. Computer-readable media includes bothnon-transitory computer storage media and communication media includingany medium that facilitates transfer of a computer program from oneplace to another. A non-transitory storage medium may be any availablemedium that can be accessed by a general purpose or special purposecomputer. By way of example, and not limitation, non-transitorycomputer-readable media can comprise RAM, ROM, electrically erasableprogrammable read only memory (EEPROM), or optical disk storage,magnetic disk storage or other magnetic storage devices, or any othernon-transitory medium that can be used to carry or store desired programcode means in the form of instructions or data structures and that canbe accessed by a general-purpose or special-purpose computer, or ageneral-purpose or special-purpose processor.

Also, any connection is properly termed a computer-readable medium. Forexample, if the software is transmitted from a website, server, or otherremote source using a coaxial cable, fiber optic cable, twisted pair,digital subscriber line (DSL), or wireless technologies such asinfrared, radio, and microwave, then the coaxial cable, fiber opticcable, twisted pair, DSL, or wireless technologies such as infrared,radio, and microwave are included in the definition of medium.Combinations of the above are also included within the scope ofcomputer-readable media.

Other examples and implementations are within the scope of thedisclosure and appended claims. For example, due to the nature ofsoftware, functions described above can be implemented using softwareexecuted by a processor, hardware, firmware, hardwiring, or combinationsof any of these. Features implementing functions may also be physicallylocated at various positions, including being distributed such thatportions of functions are implemented at different physical locations.

Also, as used herein, including in the claims. “or” as used in a list ofitems (for example, a list of items prefaced by a phrase such as “atleast one of” or “one or more of”) indicates an inclusive list suchthat, for example, a list of at least one of A, B, or C means A or B orC or AB or AC or BC or ABC (i.e., A and B and C). Also, as used herein,the phrase “based on” shall not be construed as a reference to a closedset of conditions. For example, an exemplary step that is described as“based on condition A” may be based on both a condition A and acondition B without departing from the scope of the present disclosure.In other words, as used herein, the phrase “based on” shall be construedin the same manner as the phrase “based at least in part on.”

From the foregoing it will be appreciated that, although specificexamples have been described herein for purposes of illustration,various modifications may be made while remaining with the scope of theclaimed technology. The description herein is provided to enable aperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the scope of thedisclosure. Thus, the disclosure is not limited to the examples anddesigns described herein, but is to be accorded the broadest scopeconsistent with the principles and novel features disclosed herein.

What is claimed is:
 1. An apparatus, comprising: a transceiver; adigital filter; and a switch coupled to the transceiver and configuredto: activate a switch path that provides feedback from a transmit pathof the transceiver to the digital filter via a receive path of thetransceiver or via a receive path of another transceiver; receive aselection signal indicating whether the switch path is to be activated,the selection signal based at least in part on a transmission timeinterval (TTI) of a time-division duplex (TDD) configured radio frame;responsive to the selection signal indicating the switch path is to beactivated, activate the switch path that provides feedback via thereceive path of the transceiver, and wherein the receive path of thetransceiver is coupled to the transmit path of the transceiver when theswitch path is activated, wherein an output of the switch in theactivated switch path is coupled to the receive path of the transceiver;and responsive to the selection signal indicating the switch path is tobe deactivated, activate a second switch path towards a transmitantenna, wherein an output of the switch in the second switch path iscoupled to the transmit antenna, the output of the switch in theactivated switch path is different than the output of the switch in thesecond switch path, wherein the receive path of the transceiver furthercomprises an amplifier, and when the switch path is activated to providethe feedback via the receive path of the transceiver, from the switch toan input of the amplifier.
 2. The apparatus of claim 1, wherein theselection signal indicating the switch path is to be activated is basedat least in part on an uplink TTI of the TDD configured radio frame. 3.The apparatus of claim 1, wherein the selection signal indicating theswitch path is to be deactivated is based at least in part on a downlinkTTI of the TDD configured radio frame.
 4. The apparatus of claim 1,wherein the selection signal is based at least in part on an uplink TTIof the TDD configured radio frame or a downlink TTI of the TDDconfigured radio frame.
 5. The apparatus of claim 1, wherein the digitalfilter is configured to receive the feedback via the receive path of thetransceiver when the selection signal indicates the switch path is to beactivated.
 6. The apparatus of claim 5, wherein the transceiver isconfigured to transmit communications via the transmit path of thetransceiver based at least in part on the feedback received by thedigital filter.
 7. The apparatus of claim 1, wherein the transmit pathincludes a digital to analog converter and an intermediate frequency(IF) filter.
 8. The apparatus of claim 1, wherein the receive pathincludes an analog to digital converter and an intermediate frequency(IF) filter.
 9. An apparatus, comprising: a plurality of transceiverseach configured to provide a respective signal of a plurality of signalsto a respective antenna of a plurality of antennas; a plurality of poweramplifiers configured to receive respective signals and to amplify therespective signals to generate respective amplified signals that eachinclude a portion of non-linear power amplifier noise; and a switchconfigured to: at least partially compensate the non-linear poweramplifier noise; and activate a switch path that provides feedback froma transmit path of one of the transceivers to a filter via a receivepath of that transceiver or via a receive path of another transceiver,wherein the switch is further configured to activate the switch paththat provides feedback via the receive path of the transceiver, andwherein the receive path of the transceiver is coupled to the transmitpath of the transceiver when the switch path is activated, wherein anoutput of the switch in the activated switch path is coupled to thereceive path of the transceiver, and wherein the transmit path of thetransceiver is configured to provide the respective amplified signal tothe respective antenna when the switch is deactivated, the output of theswitch in the activated switch path is different than an output of thedeactivated switch, the output of the deactivated switch is coupled tothe respective antenna, wherein the receiver path of the transceiverfurther comprises an amplifier, when the switch path is activated toprovide the feedback via the receive path of the transceiver, thefeedback is provided from the switch to an input of the amplifier. 10.The apparatus of claim 9, wherein the transmit path of that transceiverprovides feedback to the filter of that transceiver via the receive pathwhen the switch path of that transceiver is activated.
 11. The apparatusof claim 9, wherein the transmit path of that transceiver does notprovide feedback to the filter of that transceiver via the receive pathwhen the switch path of that transceiver is deactivated.
 12. Theapparatus of claim 9, wherein the respective antenna of the plurality ofantennas is configured to transmit the respective signal of theplurality of signals to a vehicle at a frequency corresponding to the 5GNew Radio (NR) band.
 13. The apparatus of claim 9, wherein the transmitpath of the other transceiver provides feedback via the receive path ofthe other transceiver when the switch path of the other transceiver isactivated.
 14. The apparatus of claim 9, wherein the receive path ofthat transceiver is configured to receive communications via the receivepath when the switch path of that transceiver is deactivated.
 15. Amethod, comprising: receiving a selection signal that indicates whethera switch path is to be activated, wherein the selection signal is basedat least in part on whether a transmission time interval (TTI) of atime-division duplex (TCDD) configured radio frame is designated foruplink transmission or downlink transmission; activating the switch pathbased at least in part on receiving the selection signal indicating theswitch path is to be activated; transmitting, after activating theswitch path, feedback from a transmit path of a transceiver to a filtervia a receive path of the transceiver or via a receive path of anothertransceiver, wherein an output of a switch in the transmit path iscoupled to the filter when the switch path is activated; coupling thereceive path of the transceiver to the transmit path of the transceiverwhen the switch path is activated; and responsive to the selectionsignal indicating the switch path is to be deactivated, activating asecond switch path towards a transmit antenna, wherein the output of theswitch in the transmit path is coupled to the transmit antenna when thesecond switch path is activated, the output of the switch when theswitch path is activated is different than the output of the switch whenthe second switch path is activated, wherein the receive path of thetransceiver further comprises an amplifier, when the switch path isactivated to provide the feedback via the receiver path of thetransceiver, the feedback is provided from the switch to an input of theamplifier.
 16. The method of claim 15, further comprising receiving theselection signal that indicates the switch path is to be activated whenthe TTI is designated for the uplink transmission.
 17. The method ofclaim 15, further comprising receiving the selection signal thatindicates the switch path is to be deactivated when the Iii isdesignated for the downlink transmission.